In the following part of the description of the present invention, a communication mobile substrate will be used as an example, in the form of a mobile telephone compatible with the GSM or equivalent networks, it being understood that the invention can also be applied to other communication substrates using radiofrequencies which are different from mobile telephones.
Mobile telephones have recently known a wide success on the international scale, so that billions of persons always have their mobile telephones with them. In this context, the mobile telephone seems to be more and more a hardware and software platform, whereon other applications than the mobile telephone application through the GSM network or an equivalent could be used.
Thus, the mobile telephone operators already provide all kinds of additional applications which are independent of the telephone application such as for example games, a digital camera, a file reader of the mp3 type and other entertainment applications. Some of the additional applications used today, such as the management of the organizer or the digital camera, use the memory of the smart card of the SIM type or the additional memory located in other formats of card intended for this purpose to store thereon the application data, which contributes to the fact that cards have always increasing memory capacities, of several hundreds of megabytes or even more. However, in the present application of the mobile telephones, the SIM card interacts with the mobile telephone using contacts positioned on the SIM card and the mobile telephone interacts with the cell telephone network, in particular under the GSM standard, using an antenna positioned on the mobile telephone.
However, considering the generalization of the mobile telephone as an application platform beyond the telephone applications, new needs have arisen since several applications which are hosted in the smart card of the SIM type or in cards of different formats, positioned in the mobile telephone such as, in a non limitative way, a “SD card”, a “mini SD card”, a Multi Media Card also called “MMC card”, could take advantage of a direct radio communication with a contactless card reader positioned in the environment of the mobile telephone or, more generally, of the communication mobile substrate. The applications for the contactless payment smart cards or the applications for the physical access control using such smart cards used as identifiers, are examples of applications which could further enhance the range of services provided by a mobile telephone. In these new contactless applications which are proximity applications in so far as the card needs to interact through a contactless coupling with a card reader which is also operated without contact, it is necessary to set up a direct radio frequency communication between the smart card reader and the card which hosts the additional application such as the payment or any other one and all this without using the cell telephone network.
Now in the mobile telephones according to the present state of the art, the smart card is in general inserted into a recess provided with contacts, so that the contacts of the mobile telephone, which is operating as a smart card reader, come in contact with the contacts of said smart card. And the recess receiving the smart card is positioned inside the mobile telephone most often opposite the battery which is used as a back cover of the telephone, the front face of the latter being used for the screen and the keypad of the telephone. Thus, the battery of most mobile telephones on the field covers a large portion of the back face of the telephone all the more so since the increasing needs for self containment tend to demand high capacity batteries which thus have larger dimensions. In addition, the metallic structure of the battery mostly made of lithium does not make it possible for the radio frequency signals used to travel satisfactorily to a contactless reader positioned in the vicinity of the mobile telephone.
This last point is an important obstacle to the development of the applications of the contactless type using a mobile telephone, since the users' mobile telephones should be massively changed.